Control means



Feb. 29, 1944. w s LANDON 2,342,633

CONTROL MEANS Filed March 5, 1941 Patented Feb. 29, 1944 CONTROL MEAN S Walter S. Landon, Detroit, Mich assignor to Detroit Lnbricator Company, Detroit, Mich, a corporation of Michigan Application March 5, 1941, Serial No. 381,835

16 Claims.

This invention relates generally to control means and more particularly to a control device having means for providing a quick or snap action and particularly adapted for controlling the flow of liquid such for example as of oil to a burner.

Anobject of this invention is to provide a new and novel means for providing a quick acting control device.

Another object is to provide novel means for predetermining the limit or range of operation of a control device.

Another object of this invention is to provide a new and novel means for controlling the fuel supply to a burner.

.Another object is to provide means for operating the fuel supply control means to maintain a heated medium between predetermined temperature limits.

Another object is to provide means whereby a valve member controlling the fuel supply is prevented from partially moving prior to movement thereof throughout its range of movement.

Another object is to provide lost motion means for connecting a valve member and a snap acting mechanism to prevent partial movement of the valve member prior to actuation thereof to full open position by the snap acting mechanism.

Another object is to provide an adjusting means for the fuel control means whereby the predetermined temperature limits may be varied.

Another object is to provide a control position whereby the control is rendered ineffective to actuate the fuel control means irrespective of the temperature of the heated medium.

The invention consists in the improved construction and combination of parts, to be more fully described hereinafter and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawing, to be taken as a part of this specification, there is fully and clearly illustrated a preferred embodiment of the invention, in which drawing:

Figure 1 is a partial view partly in side elevation and partly in vertical section of a fuel controlling apparatus embodying the invention taken along the line l-l of Fig. 2 and looking in the direction of the arrows and showing the position of the parts when the thermostatic power element is satisfied;

Fig. 2 is a top plan view of the apparatus with the cover removed and with certain parts broken away for clarity;

Fig. 3 is a view taken substantially along the Gil line 3-3 of Fig. 1 and looking in the direction of the arrows;

Fig. 4 is a view taken substantially along the line 4-4 of Fig. 1 and looking in the direction of the arrows;

Fig. 5 is a view taken substantially along the line 5-'5 of Fig. 2 and looking in the direction of the arrows; and

Fig. 6 is a fragmentary view of a portion of the apparatus and showing the relative position of certain of the parts when the thermostatic power element is dissatisfied.

Referring to the drawing by characters of reference the numeral I designates generally a fuel controlling apparatus having a lower chambered casing 2 and a hollow upper control casing 3.

The lower casing 2 has a chamber 4 which opens through the top wall 5 of the casing 2 and which is closed by the upper casing 3. The contour of easing 3 substantially corresponds to the contour of the lower casing 2 against which it is positioned and is held against the casing 2 by suitable means such as screws 6. The portion of the upper casing 3 adjacent the lower casing 2 is open and cooperates with the opening through wall 5 to provide a casing for the mechanism to be hereinafter described. The wall of the upper casing 3 opposite to the casing 2 may have an aperture 1 theretln-ough for providing easy access to the before mentioned mechanism and which aperture may be closed by a cover member 8 secured to the casing 3 by means of thumb screws 9 (only one of which is shown) extending through the cover member 8 and threaded to the bosses 10 of the casing 3.

Fuel such as oil is admitted to the chamber 4 from a suitable source of supply, througha conduit (both not shown) and through an inlet ll having a float controlled valve mechanism ii. The mechanism l2 acts to regulate the flow of fuel to the chamber l to maintain the level thereof substantially at the line L-L. The casing 2 has an upwardly extending boss l3 having longitudinally extending passageways I4 and 15. The passageways It and [5 are. joined together at their lower end portions and have a common outlet l8 which extends downward from the lower wall of the casing 2 and to which may be conneoted a conduit (not shown) for conducting the fuel from the casing 2 to a burner (not shown). Passageway It extends upward through the boss l3 and opens into the chamber 4 through the upper end ll of the boss l3 above the fuel line L--L and provides a means for. supplying atmospheric pressure to the outlet It. The passageway l extends substantially parallel to the passageway I4 and also opens through the upper end H of the boss I3. A slot l8 iscut in the boss l3 and extends longitudinally of and radially of the passageway from the end H to a point below the fuel level LL to provide a passageway for flow of fuel from the chamber 4 to the passageway I5. The lower end of the passageway 5 has a reduced diameter portion IQ for receiving a cylindrical insert member 28 which has a press fit to the walls of the portion i9 to securely hold the member and to prevent flow of fuel between the member 20 and portion IS. The member 20 extends upward from the portion l9 into the normal diameter portion of the passageway |5 and has its top wall 2| positioned below the fuel level LL. An internal transverse wall 22 of the member 20 is positiond a predetermined distance below the fuel level LL and has a central aperture 23 in which reciprocates a reduced diameter portion 24 of a valve member 25. The portion 24 has a piston-like fit with the walls of the aperture 23 so that fuel is prevented from flowing therebetween but which allows the valve member portion 24 to reciprocate relative to the wall 22. A slot 26 is cut longitudinally of the portion 24 and cooperates with the wall 22 so that upon longitudinal movement of the valve member the rate of flow of fuel past the wall 22 and into the passageway l5 for flow through the outlet l6 may be controlled. The member 25 has a conical portion 21 connecting the reduced portion 24 and the normal diameter portion of the member 25 and which cooperates at one position of the'member 25 with the top wall 2| to prevent flow of fuel from the chamber 4 to the interior of the cylindrical member 20. The valve member 25 has a passageway 21"- which opens through the lower end wall thereof into the passageway |5 on the outlet end thereof. The other end of the passageway 21- opens into the chamber 4 above the level LL to provide a means for supplying atmospheric pressure to the outlet end of passageway I5.

The valve member has a stem portion 28 of normal diameter which extends upward through the chamber 4 and into the upper casing 3 and is guided for reciprocal movement by a guide member 29 held rigid with the casing 2 as by screws 29 (only one of which is shown). Reciprocal movement of the member 25 is limited by engagement of pin members 38 and 3| which are carried by the stem portion 28 and extend radially outward therefrom. The pin members 30 and 3| engage the upper and lower surfaces respectively of an adjustable stop member 32. The stop member 32 com rises a ring-like member 33 having a portion 34 of its pe iphery cut away and having a pair of outwardly extending apertured flange portions 35. 36. Extending through the apertured flange portions 35. 36 are the high fire and low fire adju tment screws 31, 38, respectively. The screws 31, 38 have respective y lower end portions threaded into ape tures in the end H of the boss I3. The screws 31, 38 have respectively abutment portions 4|. 42 which are spaced from the end l1 and against which the flange portions 35, 36 are ur ed by helical coil springs 43, 44 located concentrically on the screws 31, 38, respectively, and which springs are pos tioned with one end against the end l1. Slots 45 in the upper ends of screws 31, 38 allow the screws 31, 38 to be threaded into and out of the boss l3 for adjustably positioning the flan e portions 35, 36 relative to the wall 22. The pin member 38 engages the ring-like member 33 adjacent the flange portion 36 and the pin member 3| engages the ringlike member 30 adjacent the flange portion 35. With this construction it is possible to adjust the high or low fire screws 31 or 38 to position the ring-like member 33 so that the high fire and low fire position of the valve member 25 may be independently adjusted.

A third pin member 41 extends radially outward from the stem portion 28 at an acute angle relative to and in the same plane as the pin member 3|. The pin members 41 and 3| cooperate with a segment 48 which projects downward from the guide member 29 intermediate the pin members 41 and 3| to prevent rotation of the valve member 25.

The upper end wall 49 of the stem portion 28 has a central threaded aperture 58 therein which receives a screw 5|. The screw 5| has a shoulder engageable with the wall 49 to limit the distance which the screw 5| may be threaded into the aperture 50 thereby to position a second shoulder 52 of the screw 5| a predetermined distance above the wall 49. The screw portion intermediate the two shoulders is of reduced diameter relative to the stem portion 28 and serves as a guide for a thrust or collar member 53 which is concentric therewith and which has a diameter substantially equal to that of the portion 28. The axial length of the collar member 53 is ess than the distance between the shoulder 52 and the wall 49 so that the collar member 53 can have limited reciprocal movement relative to the valve member 25; the movement being limited by engagement of the collar member 53 with either the wall 49 or the shoulder 52. The upper end portion of the collar member 53 has a radially extending circumferential flange 54 against which one end of a helical coil spring 54 abuts. The spring 54* is concentric with the stem portion 28, is held under compression with its other end portion abutting the guide member 29, and acts to urge the collar member 53 into engagement with the shoulder 52. Subsequent to movement of the collar member 53 into engagement with the shoulder 52, the spring 54 acts to urge the valve member 25 upward in a valve opening direction until the pin 3| engages the underside of the ring-like member 33.

The upper casing 3 has projecting inward from the opposite side walls 54 54 thereof, a pair of bosses 55 one of which is shown in detail in Fig. 5 for holding the opposite ends of a fulcrum rod 56. The ends of the rod 56 rest in recesses or grooves 51 in the upper face of the bosses 55 and are held therein by screws 51 screw-threaded within apertures in the bosses 55 so that the underside of the screw heads engage the rod 58. A transverse wall portion 58 interconnects the side walls 54, 54 of the casing 3 midway between the upper and lower end surfaces of the walls of the casing 3 and extends from one end wall 59 substantially to and underlying the bosses 55. A pressure sensitive power element 68 is secured as by screws 59' to the face of the transverse wall portion 58 facing the casing 2 and has an expansible-collapsible chamber 6| with a movable wall 62. The element 60 as shown includes a bellows member 62*. An abutment member 63 is carried by the wall 62 and extends upward therefrom and within an aperture 64 which extends through the transverse wall portion 58.

A plate-like lever member 65 has a pair of downturned ears 66 having ali ned apertures for receiving the rod 56. The lever member '65 has one end portion 31 which engages an upwardly facing shoulder 88 of the abutment member 63 and has, at its other end, portions 69, 18 and 19 extending outward therefrom. The portions 69 and 18 are bifurcated. The portion 69 has a dimple forming a downwardly facing convex surface which is adapted to en a e the upper surface of the flange 54 and, upon rotational movement of the lever member 65, acts to move the collar member 53 downward against the force of the spring 54 to move the valve member 25 downward until the pin member 38 engages the rin like member 33. As shown, the apparatus I has but one valve member 25, but a second valve member could be used and operated by portion 18 and its dimple in a manner similar to the operation of the valve member 25 by the portion 69 and its dimple for dual fuel control operation or for control of a burner igniter or other control mechanism.

The portion 19 is positioned between the portions 69 and 18 and is off-set downwardly as at 1| terminating in a downtumed lip portion 12. A strip spring member 13 of corrugated, or zig-zag, or sinuous shape having offset rebent portions 13 is positioned under stress between the portion 12 and a circumferential groove 15 of a screw 16. The downturned portion 12 has an indent 11 which receives and positions the portion of the spring member 13 which engages the portion 12. The screw 16 is threaded upwardly into a boss 18 projecting inwardly into the casing 3 from an end wall 19 of the casing 3 which is opposite to the end wall 59. v

An-internal transverse wall 88 extends between and connects the walls 54, 63 and I9 and is spaced slightly below the upper end of the easing 3. The wall 88 at its iointure with the walls 54, 54 extends to the bosses I8 but the wall portion intermediate the side walls 54, 53 is cut away in a V-shaped portion thereby to expose more of the lever member 65 to view from the top of the casing 3. The wall 80 is apertured as at 80* and has the hollow downwardly extending tubular members 8|! having openings aligned with the apertures 80' to provide a means for easy and guided access to the screws 31 and 38. The wall 88 has centrally of the walls 53 53 two upstanding annular concentric flanges 8|, 82 which have their upper end walls terminating substantially in the plane of the upper end of the casing. The cover member 8 seats against the upper end wall of the outer flange 82. The inner flange 8| is internally threaded and the wall 89 has an aperture therethrough which is aligned with the flange 8| for threaded reception of a screw adjustment member 83 which cooperates with the power element 68 in a manner to be hereinafter described, to adjust the temperature at which the power element 69 actuates the valve member 25. A knob 83 is secured to the upper end of the screw adjustment member 83 for providing an easy means for manual rotation thereof. The outer flange 82 has a projecting portion extending radially inward which has an upstandingproiection 83 The projection 83 is received within an annulus in the lower wall of the knob 83 and cooperates with an ex- The lower end of the screw adjustment memher 83 is spherical and engages one end of a leaf spring member 83 within a dimple or indented portion 69. The spring member 83 extends toward the wall 59 and lays on a bridge or fulcrum member 86 which is rigid with and carried by the transverse wall 88 intermediate the member 83 and the wall 69. The dimple 85 cooperates with the spherical end of the member 83 to correctly position the member 84 longitudinally relative to the member 86. The upper surface of the abutment member 63 has a central threaded aperture therein in which is threaded a screw 81 having a head 88 which is positioned a predetermined distance above the upper surface of the abutment member 63 by the engagement of a shoulder on the screw 81 with the abutment member 63. A U-shaped member 89 is received by the screws 81 and positioned against the head 88 with the parallel portion extending downwardly. The ends of the parallel portions preferably terminate in knife-edges 98 (only one of which is shown) for engagement with an indent in the end portion of the spring member 84 which extends toward the wall 59 and which end portion is bifurcated to receive the. screw 81. The particular construction and combination of parts shown and described provide a structure which is extremely simple to assemble. The element 63 is first secured to the wall 58 by the screws 59 and the member 83 is threaded into the aperture of the flange 8|. The fulcrum rod 56 is inserted in the apertured cars 66 and the rod 56 is placed in the grooves. 51 and locked therein by the screws 51*. The spring member 83 is then laid on the member 86 with the dimple 85 receiving the spherical end of the member 83. The screw 81 is then inserted through the member 89 and threaded into the aperture of the member 63 flexing the spring member 83 which is then held in place due to its own tension. The pring member 13 is then inserted between the screw 16 and the indent 11. The upper casing 3 can then be assembled to the lower casing 2. It is to be noted that counterclockwise movement of the lever member 65, with the casing 3 removed from casing 2, will be limited by engagement with the transverse wall portion 58 to prevent the spring 13 from causing undue rotation thereof.

The power element 60 comprises the expansible-contractible chamber 6|, the movable wall 62 and a bulb element 9| communicatively connected to the chamber 6| by a small bore or capillary tube 92. The bulb element 9|, tube 92 and chamber 6| are charged with a temperature sensitive volatile fluid which has a vapor pressure below atmospheric throughout the entire range of temperatures for which the bulb 9| that irrespective of any setting of the member 83, the movable wall 62 would be moved upward to close the valve member 25. The bulb element 9| is secured in good heat exchange relation with the medium which is to be heated by the burner so that the medium and bulb temperatures are substantially the same or at least are proportional to each other.

The operation of the apparatus is as follows:

, In the position of the apparatus as shown in F g. 1, the medium heated by the burner has reached the maximum temperature required to close the valve and has not yet been reduced in temperature suilicient to actuate the valve 25 to open position. As shown, the low fire adjustment screw 38 is in a position permitting the valve member 25 to be moved to full closed position with the conical portion 21 engaging the inner niting the fuel supplied to the fuel burner upon a call for heat by the medium heated by the burner as reflected by the bulb 9| which is in heat exchange relation therewith. The low fire screw 38 may be adjusted so that upon engagement of the pin member 30 with the ring-like member 33 the valve member is maintained in a position to supply a predetermined low or minimum flow of fuel to the burner so that it will remain at pilot fire. In such an event, it will be noted, the necessity for an automatic ignition means is obviated.

As the temperature of the heated medium falls, the temperature of the bulb 9| will also fall condensing therein a greater amount of the volatile fluid and reducing the fluid pressure within the expansible-contractible chamber 6|. Upon attainment of the predetermined desired minimum temperature of the heated medium, the pressure within the expansible-contractible chamber 6| will have been lowered suillciently so that the atmospheric pressure acting on the movable Wall 62 will overcome the upward force of the spring 84. The movable wall 62 will then move downward allowing the lever member 65 to move to the position shown in Fig. 6 and allowing the portion 69 to move upward under the influence of the spring 54 thereby causing the collar member 53 to move upward into engagement with the shoulder 52. The clockwise rotation of the lever member 65 will allow the spring 5| to move'the valve member upward away from its seat until the pin member 3| engages the under side of the.

ring-like member 33 at which time further upward movement of the valve member will be limited. Clockwise rotation of the lever member 65 will continue until the portion 10 engages the under face of the bridge member 86 to limit its movement, see Fig. 6. The spring 13 exerts a component of force opposing clockwise movement of the lever member 65 but as the lever member 65 rotates this component decreases continually, and subsequent to the movement of the point of engagement of the spring with the lever member past a line of centers drawn between the fulcrum rod 56 and the groove 15, the spring I3 exerts an increasing component of force urging the lever member 65 toward clockwise movement. The

spring-84 opposes the clockwise movement of the lever member and due to the flexing thereof upon said lever member movement the opposing force of spring 84 increases. I The spring 54, it will be observed, acts to urge the collar member 53 upward and the lever member 65 in a clockwise direction and upon engagement of the collar member 53 with the shoulder 52 will also act to lift the valve member 25. The net force of spring 54 acting against the lever member 65 will be greater during the initial movement of the member 65 than it will after the collar member 53 has engaged the shoulder 52 and after the spring 54 has increased in length due to movement of the collar member 53.

The forces of the springs 54*, 13 and 84 and of the resiliency of the bellows 62 are so arranged that upon initial movement of the lever member 65 in a clockwise direction the sum total of the force components exerted by the springs 13 and 84 and by the bellows 62 in opposition to the clockwise movement of the lever member 65 decrease more rapidly than the decrease in net force exerted by the spring 54 in the aid of clockwise movement of member 65 so that a constant force exerted on the movable wall 62 will cause complete movement of the member 65 throughout its range of movement. However due to the inevitable friction between the lever member 65 and its fulcrum rod 56 and the friction in the remainder of the moving parts, the lever member 65 will be slightly moved in a counterclockwise direction facing Fig. 1 prior to the occurrence of the pressure within the chamber 6| necessary to cause complete movement of the member 65 throughout its range. This slight movement, however, is related to the range of movement ofthe collar member 53 so that the member 53 will not engage the shoulder 52 and no movement of the valve member 25 will occur until the pressure necessary for complete movement has been reached within the chamber 6|. The component of the spring forces urging the lever member in a counterclockwise direction will then be sufficient so that movement subsequent to engagement of the collar member 53 with the shoulder 52 will cause the valve member 25, once it is initially moved, to be moved by the lever member 65 completely throughout its range.

Subsequent to the opening of the valve member 25 to supply fuel through the outlet IE to the associated burner, the heat output from the burner will be increased thereby to raise the temperature of the heated medium. A predetermined increase in temperature of the heated medium and consequently the bulb 9|, will cause the fluid within the bulb 9| to volatilize and increase the pr s ure within the expansible-contractible cha er 6|.- The occurrence of a predetermined pressure within the chamber 6| will cause the movable wall 62 to move in an upward direction to move the lever member 65 in a counterclockwise direction so that the portion 69 will engage the upper surface of the flange 54 of collar member 53 and move the collar member 53 downward against the resilient force of the spring 54.

It will be noted that the under face of the bridge member 86 is positioned so that the lever member 65 when in its extreme clockwise position is spaced from the upper face of the flange 54. By this positioning of the lever member 65, any initial movement of the member 65 in a counterclockwise direction will be similar to the initial clockwise movement thereof as described hereinbefore; This movement will occur prior to the necessary decrease in pressure within the chamber 6| but will not cause any movement of the valve member 25. Subsequent to the movement of member 65 in a counterclockwise direction sufficient to engage the flange 54, the force components of springs 13 and 84 and of the bellows 62"- will have adjusted themselves such that the sum total thereof has increased sumciently to overcome the opposing net force component of the spring 54 so that the valve member 25 upon initial closing movement is moved completely through its range of movement and until the pin member 30 engages the stop member 32. Should the force of the gravity acting on the valve member 25 be greater than any frictional force tending to prevent movement of the valve member 25, the valve member will immediately begin to move toward closed position upon engagement of the portion 89 with the flange 54. Movement of the valve member 25 toward closed position is limited by engagement of the pin member 30 with the upper Surface of the ring-like member 33. Upon limitation of movement of valve member 25 as described, counterclockwise movement of the lever member 65 will continue until the collar member 53 engages the upper end wall 49 of the'stem portion 28, the parts will then be in the original position as shown. The force exerted by the springs 43 and 44 is such that any normal force exerted by the lever member 54 tending to move the valve member 25 toward closed position will not cause the member 32 to be moved out of engagement with the abutment portions 4| and 42. In other words, the stop member 32 is immovable except as it is moved by the screw member 31 and/or 38.

Should it be desired to change the predetermined range of temperatures of the heated medium, such may be accomplished by means of the adjustment screw 83 by the knob 83. Movement of the screw 83 in a downward direction acts to flex the spring 84 causing it to exert a greater upward force on the movable wall 82 lowering the predetermined temperature at which the bulb 9| acts to move the valve member with consequent lowering of the average temperature at which the heated medium is controlled. Conversely, movement of the screw 83 in an upward direction reduces the upward pull on the wall member 82 exerted by the spring 84 and raises the temperature limits maintained by the heated medium.

The force exerted by the spring 84 is so proportioned, relative to the force exerted by the pressure within the expansible-contractible chamber 8!, that in the extreme downward position of the screw 83 the occurrence of an absolute vacuum within the chamber 6| will not cause the valve member 25 to be moved to open position. By such an interrelation, it is possible merely by adjusting the screw 83 to minimum fire position to maintain the valve member 25 in its low fire or out-fire position, as determined by the setting of screw 38, and irrespective of the temperature of the medium heated by the burner.

It may thus be seen that with the described invention there is provided a means to prevent any movement of the valve member 25 in a valve opening direction prior to movement of the valve member away through the maximum open position thereby preventing a seepage flow of fueldue to the valve member being moved slightly from its seat. It may also be seen that without any complicated mechanical interlock, a single temperature adjusting means may be positioned to maintain the valve member 25 in minimum flow position irrespective of the temperature of the heated means. This lastnamed feature is particularly desirable as a simple means for rendering the burner ineffective to heat the heated medium should there be a prolonged absence of a desire for such heatmg.

What is claimed and is desired to be secured by Letters Patent of the United States is:

1. In a device of the character described, a

pressure sensitive power element, a movable controlling member, motion transmitting means movable by said element, force exerting means acting on said transmitting means and operable to cause said transmitting means to move with a quick action, a thrust member engaged and movable with said transmitting means and having limited lost-motion relative to said controlling member, said thrust member having its limit of lost-motion in one direction established by its engagement with said controlling member, said thrust member acting at said limit to connect postively said controlling member to said transmitting member so that said controlling member moves with said transmitting member, said thrust member during said one direction lostmotio permitting said transmitting means to be in motion prior to movement of said controlling member, the extent of said one direction lost-motion movement being such that the operating pressure of said power element necessary for complete movement of said controlling member will be reached before said thrust'member connects said controlling member to said transmitting means.

2. In a control device, a housing, a power element carried by said housing, a movable controlling member having at least a portion within said housing, a fulcrum member carried by said housing, a plate-like resilient member fulcrumed on said fulcrum member and having one end portion operatively connected to said element and having another end portion positioned on the other side of said fulcrum member from said element, means carried by said, housing and operable to position said resilient member other end portion and to hold said resilient member under stress to control the operation of said power element, movable connecting means interconnecting said controlling member and said element for movement of said controlling member by said element, a first spring acting to maintain said connecting means in engagement with said element, and a second spring cooperable with said first spring and 'said resilient member to cause said connecting means to move with a quick movement.

3. In a control device, a housing, a power element carried by said housing, a movable controlling member having at least a portion within said housing, a fulcrum member carried by said housing, a plate-like resilient member fulcrumed on said fulcrum member and having one end portion operatively connected to said element and having another end portion positioned on the other side of said fulcrum member from said element, means carried by said housing and operable to position said resilient member other end portion thereby to hold said resilient member under stress to control the operation of said power element, a lever member fulcrumed in said housing and having one portion engageable with said element and having another portion operatively connected to said controlling member, a corrugated resilient thrust member positioned under stress between a portion of said lever member and said housing, and a spring acting on said lever member and operable, irrespective of any opposing force exerted by said corrugated member, to maintain said lever member in constant engagement with said element.

4. In a device of the character described, a pressure sensitive power element having a movable wall, a resilient member opposing movement of said movable wall in one direction, means holding said member under stress, means for moving said holding means between two positions for changing the degree of stress of said resilient member, said movable wall being moved in said one direction against the force of said resilient member upon a decrease in pressure within-said element when said holding means is in one of said two positions, means limiting movement of said movable wall in a direction opposite to said one direction, said resilient member being so constructed and arranged relative to said element that when said holding means is in the second of said positions and with an absolute vacuum in said element said resilient member will. hold said movable wall against solid limiting means and will oppose movement of said movable wall with sui'licient force to prevent movement of said movable wall in said one direction thereby to render said power element inefiective.

5. In a device of the character described, a power element, a lever member moved by said element, a controlling means having two positions of operation, a movable means for actuating said controlling means to each of said positions and having a stem porton, a pair of spaced shoulders carried by said stem portion, a sleeve member carried by said stem portion and movable relative to said stem portion and engageable upon movement with said shoulders to limit said relative movement, means urging said sleeve member into engagement with one of said shoulders and operable to move said movable means in one direction to actuate said controlling means to one of said positions, said lever member having a portion engageable with an operable to move said sleeve member in a second direction against the force of said urging means and into engagement with the other of said shoulders and to hold said controlling means in a second of said positions, said relative movement acting to allow movement of said sleeve member prior to actuation of said controlling means in said one direction.

6-. In a device of the character described, a power element, a lever member moved by said element, a controlling means movable to two controlling positions, a movable means for actuating said controlling means and. having a stem portion, a pair of spaced shoulders carried by said stem portion, a sleeve member carried by said stem portion and movable relative to said stem portion and engageable with said shoulders to limit said relative movement, stressed means acting on said sleeve member and acting upon engagement of said sleeve member with one of said shoulders to move said controlling means to one of said controlling positions, said lever member having a portion engageable with and operable to move said sleeve member against the force of said stressed means and into engagement with the other of said shoulders and upon engagement of said sleeve member with said other shoulder to positively move said controlling means to the other of said controlling positions, said relative movement acting to allow movement of said sleeve member prior to movement of said controlling means by said stressed means toward said one controlling position, and means for determining said controlling positions.

7. In a device of the character described, a power element, a lever member movable in two directions and moved by said power element, a controlling means movable to two controlling positions, a movable means for actuating said controlling means and having a stem portion, a pair of spaced shoulders carried by said stem portion, a sleeve member carried by said stem portion and movable relative to said portion and engageable with said shoulders to limit said relative movement, stressed means acting on said sleeve member and acting upon engagement of said sleeve member with one of said shoulders to move said controlling means to one of said controlling positions, said lever member having a second portion engageable with an operable upon movement in one of said two directions to move said sleeve member against the force 01. said stressed means and into engagement with the other of said shoulders and to move said controlling means to the other of said controlling positions, said controlling means upon movement of said lever member in the other of said directions to be moved to said one controlling position, said relative movement acting to allow movement of said sleeve member prior to initial movement of said controlling means in said one direction, and means limiting movement of said lever member in said, other direction, said limiting means being so related to the movement of said movablemeans that said lever member can have movement subsequent to limitation of movement of said controlling means to said one controlling position.

8. In a device of the character described, a power element, a lever member moved by said element, a controlling means movable to two controlling positions, a pair of spaced shoulders carried by said controlling means, a sleeve member carried by said controlling means and movable relative thereto and engageable with said shoulders to limit said relative movement, stressed means acting on said sleeve member and acting upon engagement of said sleeve member with one of said shoulders to move said controlling means to one of said controlling positions, said lever member having a portion engageable with and operable to move said sleeve member against the force of said stressed means and into engagement with the other or said shoulders and upon engagement of said sleeve member with said other shoulder to positively move said controlling means to the other of said controlling positions, means cooperable with said power element for moving said lever member with a quick movement in one direction, said relative movement acting upon movement of said lever member in said one direction to allow movement or said sleeve member prior to movement of said controlling means' by said stressed means thereby to allow said lever member to be in motion prior to initial movement of said controlling means toward said one controlling position.

9. In a control apparatus for an oil burner, a casing having a chamber with an inlet and an outlet, means controlling flow through said inlet and acting to maintain a predetermined substantially constant level of oil therein, valve means controlling flow of fuel through said outlet, temperature sensitive means responsive to a medium heated by the burner and having a movable actuating portion, a lever member fulcrumed on said casing and having a portion engageable with said actuating portion, said valve means having a pair of spaced shoulders, a sleeve member positioned between said shoulders, said sleeve member having reciprocal movement and being engageable with said shoulders, a helical coil compression spring positioned under stress between said casing and said sleeve member and 2,a42,ess

acting to urge said sleeve member into engagement with one of said shoulders, said lever member having a second portion engageable with said sleeve member and operable upon movement by said temperature sensitive means to move said sleeve member against the force of said spring into engagement with the other of said shoulders, said lever member having a third portion, and overcenter means carried by said casing and engageable with said third portion and operable to cause said sensitive means to move said lever member with a quick action.

10. A thermostatic device comprising, a supporting member, a temperature sensitive power element carried by said member and having a movable portion, a pair of spaced abutments facing each other and carried by said movable portion, lever means fulcrumed on said member and having one end portion abutting one of said spaced abutments, said means being operable to be moved upon movement of said movable portion, a bridge member rigid with said casing, a thrust member secured to said casing on the other side of said bridge member from said movable portion, a leaf spring positioned against said bridge member and having one end portion engageable with the other of said spaced abutments and having its other end portion underlying said thrust member, said thrust member acting to hold said spring under stress and against said bridge member and spring means acting on said lever means to hold said lever means one end portion constantly in engagement with said one spaced abutment and cooperating 'with said leaf spring upon movement of said movable portion in one direction to cause said lever means to move with a quick movement.

11. A thermostatic device comprising, a supporting member, a temperature sensitive power element carried by said member and having a movable portion, a pair of spaced abutments facing each other and carried by said movable portion, lever means fulcrumed on said member and having one end portion abutting one of said spaced abutments, said means being operable to be moved upon movement of said movable portion, a bridge member rigid with said casing, a thrust member secured to said casing on the other side of said bridge member from said movable portion, a leaf spring having longitudinally slidable engagement with and seating on said bridge member and having one end portion engageable with the other of said spaced abutments and having its other end portion underlying said thrust member, said thrust member acting to hold said spring under stress and against said bridge member, and means on said thrust member and cooperable with said spring other end portion to position said spring longitudinally on said bridge member and to position said spring one end portion relative to said other spaced abutment.

12. A control device comprising, a housing member, a pressure sensitive power element carried by said member and having a movable wall, an abutment member carried by said wall and having an engaging surface, alever member fulcrumed on said housing member and having a first portion engageable with said surface and having a second portion, means engageable with said second portion and actuated upon movement of said lever member, resilient means urging said first portion into engagement with said surface, a fulcrum member carried by and rigid with said housing member and spaced from said abutment member, a leaf spring positioned against said fulcrum member and having one end portion overlying said surface and having a second portion extending beyond said fulcrum member on the other side thereof from said one end portion, means positoned in facing relation to said surface and secured to said abutment member and engageable by said spring one end portion, means carried by said housing member and engageable with said spring second portion and operable to place said sprin under stress thereby to hold said spring against said fulcrum member and in engagement with said secured means, said lever member having a third portion extending beyond said second portion, and a second spring separate from said urging means for exerting a variable force on said lever member third portion and cooperable with the force exerted by said spring and said urging means to cause said lever member to move with a rapid movement subsequent to initial movement by said power element.

13. In a device of the character described, a power element, a member moved by said element, a controlling means having two positions of operation, a pair of spaced abutments carried by said means, a sleeve member carried by and movable relative to said means and engageable upon movement with said abutments to limit said relative movement, means urging said sleeve member into engagement with one of said abutments and operable to move said controlling means in one direction to one of said positions, said first-named memberha g aportion engageable with and operable to move said sleeve member in a second direction against the force of said urging means and into engagement with the other of said abutments and to hold said controlling means in a second of said positions, said relative movement acting to allow movement of said sleeve member prior to actuation of said controlling means in said one direction.

14. An apparatus of the character describe comprising, a supporting structure,- a power means carried by sad structure and having a force exerting element, spaced abutments carried by said element in opposed facing relation, thrust means, carried by said supporting structure and laterally offset from said element, a lever member fulcrumed on said structure and having a portion engageable with one of said spaced abutments and having a portion extending toward and below said thrust means, an, elongated resilient strip member extending substantally parallel to and overlying said lever member and having one end portion engageable with the other of said spaced abutments and having another end portion engageable with said thrust means, a fulcrum member carried by said structure and holding said strip member under stress, controlling means actuated by said lever member extending portion and a spring acting to hold said lever member in engagement with said one abutment, said spring and said resilient member tending to move said abutments away from each other, thereby to assure transmission to said lever member of any movement by said power means.

15. In a device of the character described, a power element, a lever member moved by said element, a controlling means movable to two controlling positions, a movable means for actuating said controlling means and having a stem portion, a shoulder carried by said stem portion, a sleeve member carried by said stem portion and tive movement, stressed means acting on said sleeve member and acting upon engagement of said sleeve member with said shoulder to move said controlling means to one of said controlling positions, said lever member having a portion engageable with and operable to move said sleeve member against the force of said stressed means to permit said controlling means to move to the other of said controlling positions, said relative movement acting to allow movement of said sleeve member prior to movement of said controlling means by said stressed means toward said one controlling position, and means for determining said controlling positions.

16. In a device of the character described, av

power element, a lever member moved by said element, a controlling means movable to two controlling positions, a movable means for ac- 90 tuating said controlling means and having a stem portion, an abutment carried by said stem portion, means carried by said stem portion and movable relative to said stem portion and engageable with said abutment to limit said relative movement, stressed means acting on said carried means and acting upon engagement of said carried means with said abutment to move said controlling means to one of said controlling positions, said lever member having a portion engageable with and operable to move said carried means against the force o1 said stressed means to permit said controlling means to move to the other of said controlling positions, said relative movement acting to allow movement of said carried means prior to movement of said controlling means by said stressed means toward said one controlling position, and means for determining said controling positionsl WALTER S. LANDON. 

